Field of the Invention
The present invention relates to a process for changing a running direction of an electromagnetically guided driverless vehicle. A conventional electromagnetically guided driverless vehicle has right and left drive wheels mounted under the vehicle body at both sides, and front and rear idle wheels mounted at opposite ends of the vehicle with respect to the drive direction. The driverless vehicle is guided by detecting a magnetic field generated by a guide path, such as a conductor wire energized by a high frequency current. The guide path is well known in the art which is comprised of either a single conductor wire forming a closed loop along the whole route on which the driverless vehicle is guided, or two parallel going conductor wires laid on the route in such an arrangement that the current flows through the two parallel going conductor wires in an opposite direction to each other. The above two methods of guiding a driverless vehicle can be applied to the present invention, and in the former case the driverless vehicle has a single route sensor for detecting the magnetic field, while in the latter the driverless vehicle has two route sensors each corresponding to respective two parallel going conductor wires.
A typical route arrangement adopting the two parallel going conductor wires is illustratively shown in FIG. 1, in which an oscillator 1p drives two parallel going conductor wires 2p and 3p which constitute a guide path along which an electromagnetically guided driverless vehicle 4p is guided. The vechicle 4p has right and left drive wheels 5p and 6p, front and rear idle wheels 7p and 8p, and two route sensors 9p and 10p. According to the prior art technique for changing a running direction of an electomagnetically guided driverless vehicle, there are some disadvantages that when the vehicle 4p is directed at a turning point A to the route .beta., it is necessary to have at least a turning radius of one half the body length of the vehicle 4p as shown in a dotted line, since the route sensors 9p and 10p must always trace the two parallel conductor wires 2p and 3p. Thus, it has been impossible to turn at the turning point A following the route as shown in a solid line. Furthermore, if it is required to shuttle the vehicle 4p at a route .alpha., the need arises for providing additional pair of route sensors at the opposite side of the route sensors 9p and 10p relative to the longitudinal direction of the vehicle body, thus resulting in a high cost. In addition to the above, if the loading and unloading side is limited only to one side of the vehicle body, the loading and unloading side is confined to one side of the whole route, thus reducing an efficiency of working.